The main aims behind a series of projects involving pregnant hamsters infected with a number of different viruses - including the Minute Virus of Mice (MVM), Parainfluenza viruses Types 2 and 3, and Newcastle Disease Virus (NDV) - are to study transplacental and neonatal infections. Separate and additional projects include studies on Spontaneous Hemorrhagic Necrosis of fetal hamsters, attempts to isolate the agent causing digital fibromas in children, and efforts to adapt Rat Cytomegalovirus to laboratory rats.